Electromagnetic device



D. D. MILLER.

ELECTROMAGNETIC DEVICE.

APPLICAHON FELD DEC. 10, 19:2.

1,339,778, Patented May 11, 1920.

m 35 9 I 7, (A

\ Milli N /n venfor: D nv'e/ 0. M/Y// UNITED STATES PATENT OFFICE.

DANIEL D. MILLER, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ELECTROMAGNETIC DEVICE.

Specification of Letters Patent.

Patented May'll, 1920.

To all whom it may concern:

Be it known that I, DANIEL D. Minnnn, a citizen of the l nited States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Electromagnetic Devices, of which the following is a full, clear, concise, and exact description.

This invention relates to electromagnetic devices and in particular to a sensitivepolarizing relay especially suitable for use in connection with high speed telegraph apparatus.

lVith the present type of high speed relays trouble is continually being experienced, due to the slight changes in adjustment, resulting from the use of constructions employing pivoted bearings and knife edges. In view of the small air gaps and delicate adjustments necessitated by the requirement of high sensitiveness a very slight wear of the moving parts or a change 1n adjustment makes the relay inoperative and expert adjustment is required.

Again in connection with long loaded telephone lines which are used for telegraph work the presence of the loading coils makes it necessary to keep down the amplitude of a the telegraph or Morse currents in order to prevent making the lines noisy, and therefore for this service a relay is required which is more sensitive than those ordinarily employed on long telegraph lines where the amplitude of the current is not necessarily limited.

It is, therefore, the object of the present invention to provide a polarized relay of high sensitiveness and one in which the construction is such asto allow its use under commercial conditions without requiring readjustment or expert attention. Another object is to provide a relay in which all of the adjustments may he made without interfering with or necessitating the removal of the relay from its operating circuit. A further object is to provide a sensitive biasing arrangement which will permit of quick and accurate biasing of the armature. A still further object is to provide an armature construction permitting a very high degree of sensitiveness.

To accomplish these objects a feature of the invention resides in the employment of a balanced magnetic circuit having the armature fixed at one end, that is, an armaing provide ture of the cantaliver beam type and balancing out the polarizing flux by the stiffness of the armature itself. Another feature consists in the employment of an armature biasing arrangement comprising a light flexible s rlng carried by the armature itself and a justable means for flexing this spring in e ther direction. Still another feature conslsts in reducing the cross section of the armature at a given point in order that its sensitiveness be not impaired when operating under the severe service conditions re sulting from unequal positive and negative current impulses rapidly following each other.

Still other features will be brought out more clearly in the following specification and in the accompanying drawing, in which F igure 1 is a perspective view of a relay embodying this invention; and Fig. 2 is a. plan view of certain parts of the structure.

Referring now to the drawing in which there is illustrated a relay embodying this invention, there is shown a relay frame 4 of brass or other non-magnetic material, this frame being equipped with standards or mounting lugs 5-5, provided with mounting holes 66, Whereb the device may be attached to any suitab e base. This frame is also provided with projections or bosses 7 7 for the purpose of supporting an adjusting device to be described hereinafter. Supported at one end of frame 4, and secured thereto by means of screws 8-8, are the pole pieces 9-9 of magnetic iron, and which ma be built up of thin sheets or laminations i the apparatus is to be operated by currents of very high frequencies. The armature 10 is rigidly clamped between the pole pieces 9--9, but separated therefrom by the non-magnetic shims 11-11. By the use of these shims, high reluctance gaps are provided between the pole pieces 9-9 and the armature 10, thereby providing magnetic poles andfixed air-gaps where the armature is clamped in position. As a result of this construction, the effects of re- Sidual magnetism are largely overcome and the desired balanced magnetic circuit is retained with its advantages of high sensitivity. The clamping screws 1212 engage the threaded ortions 13-13 of frame 4, be-

for clamping these parts together. After the clamping screws 12l2 are tightened, the screws 88. which pass through oblong holes or slots in the pole pieces, are tightened, seating these parts securely upon the frame. Pins 14-14 of brass or other non-magnetic material are provided to facilitate bringing the parts in correctalinement.

In order to make the operation of the relay more sensitive, as will be explained hereinafter, when operating with wave forms of opposite polarity and of alternately high and low amplitude, the armature 10 is provided with notches 15-15, as shown, in order to cut down its cross section at this point.

One end of each of the pole pieces 9-9 is provided with a threaded hole adapted to engage the threads of the adjusting screws 16-16 which are of magnetic material and act as extensions to the pole pieces. Saw slots 17-17 are also provided in the pole pieces, as shown, so that when the screws 16-16 are once adjusted they may be locked in position by tightening the screws 18-18.

The relay operating coil 19 is provided with spool heads 20-20, one of which has a slight angled projection permitting it to be securely fastened to the frame by means of the screw 21. The hollow core of this coil is so dimensioned as to allow ample clearance for the operation of the armature 10. In alinement and on opposite sides of the armature are the contact screws 22-22 passing through threaded openings in the bracket members 23-23, which in turn are secured to the frame 4 by means of screws 24-24, but are insulated therefrom by means of the insulating plates 25-25 and the insulating washers 26-26. -A terminal clip 27-27 is provided at each bracket to facilitate making the necessary connections. 1 The brackets 23-23 are provided with saw slots 28-28 which coiiperate with the screws 29-29 to permit locking the contact screws 22-22 securely in position after the adjustment is once made. Each contact screw is fitted with a tip of platinum or other suitable contact material and is adapted upon vibration of the armature to engage the contact parts 30-30, which are of a similar material and are securely fastened to the armature.

The means for polarizing this relay con-' sists of a U-shaped permanent ma net 31, and a pair of polar extension mem ers 32, only one of which is shown on the drawing. These members are secured to the pole pieces 9-9 by means of screws 33-33. The ends of the magnet 31 are drawn against the lower end of polar extension members 32- 32, by means of the clamping bar 34 which is of brass or other suitable non-magnetic material. A stud 35 fastened at one end to the frame 4, passes through the hole in the clampin bar 34 and is threaded to receive a clamping nut which permits drawing the parts together.

A screw 36 passing through a perforation in the relay frame 4 supports the closed end of the permanent magnet. In order to obtain the correct strength of permanent magnet, a slidable keeper 37 is provided to furnish a shunt path for a portion of the flux of the permanent magnet, the position of this keeper determining the amount of diverted from the magnetic circuit of the relay proper. The desired movement of this keeper is brought about by turning the knurled head of the adjusting screw 38. This screw engages a threaded opening in the member 39, this member in turn bein loosely pinned to thekeeper in order to a low the latter to be drawn into intimate contact with the permanent magnet by the maIgnetizing force of the magnet itself.

11 view of the small air gaps required on a relay of this. type, it is practically impossible to locate the armature so that it will be perfectly balanced Without resorting tosome type of biasing arrangement. In the present case the biasing arrangement consists of a light, flexible spring 40, rigidly secured to and in line with the armature, and an adjusting device which rmits the supporting of the free end of spring 40 at either side and at a given position. This device consists of a rod 41 slidable through perforations in the bosses 7-7 and having one end grooved or otherwise shaped to prevent its rotation. The other end of this rod is threaded to engage the adjusting nut 42, the shouldered end of which is held against the outside of the boss 7, by means of a helical spring 43 fitting over the recessed portion of the rod 41 and compressed between the shoulder portion of this rod and the inside of the boss. Secured to the rod 41 by means end of spring 40 and carries a pair of knife edges 46-46 separated by a distance slightly greater than the thickness of the spring 40 so as not to cause buckling of this spring. The other end of this punching acts as a pointer and registers with the calibrated scale on the bracket piece 47, this bracket being secured to the bosses 7-7 by means of the screws 48-48. A knurled-head thumb screw 49 is provided to lock the rod 41 in position after the adjustment is once made.

The hi 11 sensitivity of the structure just described will at once be apparent by considering its operation. \Vith no current flowing through the energizing winding the flux from the permanent magnet exerts a pull-on the armature in either direction but any movement of the armature is prevented by thecantaliver beam type of armature which is in a neutral osition as regards the pole pieces. The sti ness of this armature however, is only slightly greater than is necessary to ofi-set the polarizing bias or the pull exerted by the permanent magnet and therefore a very small flux generated in the armature by a current flowing through the energizing winding is sufliclent to cause movement ofthe armature and the subsequent closure of the contact members. In any polarized relay the force tending to cause movement of the armature is the difference between the force due to the operating current and the biasing force due to the permanent magnet. The operating force, that is, the force due to the operating current flowing in the winding, is proportional to the product of the flux due to the ampere turns and the flux due to the permanent magnet. The biasing force, due to the permanent magnet, is proportional to the square of the permanent magnet flux. For these reasons it is highly desirable to make the polarizing flux large in order to obtain a sensitive piece of apparatus, but in the common type of pivoted relay this is not practical since the armature will normally be biased to one side or the-other and the operating force must therefore be greater than the biasing force in order to cause movement of the armature. However, in the present structure, since the polarizing bias is practically counterbalanced mechanically by means of the cantaliver beam type of construction used, it is possible to-obtain high sensitivity by increasing the polarizing flux. Still another advantage is gained by being able to in crease the polarizing flux since it permits the working of the iron parts at the most favorable flux density. This construction also has a decided advantage in freedom from mechanical troubles inherent in structures which employ pivot bearings or knife edges.

Increased sensitivity under certain conditions also results from employing an armature provided with notches as shown in the structure described. Especially in telegraphic work it is often require to o crate a relay with pulsations of opposite po arity. Under such conditions if a pulsation of one polarity and of high amplitude is immediately followed by a pulsation of the opposite polarity and low amplitude the sensitive operation of the relay depends quite largely upon the residual effect of the armature itself. The constricted portion of the armature brought about by employing the notches as shown aids 1n causing its demagnetization and therefore brings about greater sensitiveness under such wnditions.

What is claimed is:

1. An electromagnetic device comprising a permanent magnet, an ener izing coil, an armature extending theret rough, and

means including said armature and exclusire of said coil for counterbalancing the greater portion of the polarizing bias of said permanent magnet in either direction.

2. An electromagnetic device comprising an energizing coil, a permanent magnet having pole pieces therefor, and an armature supported between said pole pieces as a cantaliver beam and extending through the coil, said armature being so arranged and proportioned that the resistance of the beam to bending in either direction nearly counterbalances the polarizing bias of said permanent magnet.

3. An electromagnetic device comprising a polarizing magnet, a pair of bifurcated pole pieces for said magnet, each of said pole pieces comprising a fixed limb and an adjustable limb, an armature clamped between said fixed limbs, an energizing coil encircling said armature, a circuit changing device operated by said armature, and an armature biasing device.

4. An electromagnetic device comprising a permanent magnet. a pair of pole pieces for said magnet. each of said pole pieces comprising a. fixed limb and an adjustable limb. an armature clamped between said fixed limbs and adapted to vibrate between said adjustable limbs, and an energizing coil encircling said armature.

An electromagnetic device comprising a permanent magnet. a pair of pole pieces for said magnet, each of said pole pieces comprising a fixed limb and an adjustable limb, an armature clamped between said fixed limbs, means for magnetically insulating said armature from said pole pieces, and an energizing coil encircling said armature.

6. An electromagnetic device comprising a permanent magnet, a. pair of pole pieces for said magnet, each of said pole pieces comprising a fixed limb and an adjustable limb, means for locking said adjustable limbs in position, a cantaliver beam armature clamped between said fixed limbs and adapted to vibrate between said adjustable limbs, and an energizing coil encircling said armature.

7. An electromagnetic device comprising a permanent magnet, a pair of pole pieces for said magnet, each of said pole pieces comprising a fixed limb and an adjustable limb, an armature clamped between said fixed limbs and adapted to vibrate between said adjustable limbs, the cross section of said armature having a restricted portion intermediate its ends, and an energizing coil encircling said armature.

8. An electromagnetic device comprising a permanent magnet. a pair of pole pieces for said magnet, each of saidpole pieces comprising a fixed limb and an adjustable limb, an armature clamped between said fixed limbs, means for positioning said ole pieces with res ect to said armature, a ditional means or magnetically insulating said armature from said pole p eces, and an energizing coil for said armature;

9. An electromagnetic device comprising a permanent magnet, a pair of bifurcate pole pieces for said magnet, each of said pole pieces comprising a fixed limb and an adjustable limb, an armature clamped be-' tween said fixed limbs, means formagnetically insulating said armature from said pole pieces, a contact member carried by said anna'turefa second contact member adapted to be en aged by said first contact member upon viiration of said armature, and an energizing coil for said armature.

10. An electromagnetic device comprisin a permanent magnet, a pair of bifurcatec pole pieces for said magnet, each of said pole pieces comprising a fixed limb and an adjustable limb, an armature clamped between said fixed limbs, an energizing coil encircling said armature, a circuit chan ing device operated b said armature, an an armature biasing device including a flexible extension for said armature and a means for supporing the free end of said extension member.

11. An electromagnetic device comprising a ermanent magnet, a pair of bifurcated po e pieces for said magnet, each of said pole pieces comprising a fixed limb and an adjustable limb, an armature clamped bei coi tween said fixed limbs, an energizin encircling said armature, a circuit 0 anging device operated by said armature, an

. means, and

armature biasin device including a spring member attache to said armature in alinement therewith, and an adjustable means for supporting the free end of said spring member. 7

12. An electromagnetic device comprising a ermanent magnet, a pair of bifurcated p0 e pieces for said magnet, each of said pole pieces comprising a fixed limb and an adjustable limb, an armature clamped between said fixed limbs, an energizing coil encircling said armature, a circuit changing device operated said armature, an armature biasing device includin a flexible spring mem er attached to sai armature, a pair of knife edgesseparated from each other a distance slightly greater than the thickness of said spring member, and means for adjusting the position of said knife edges.

13. An electromagnetic device comprising a permanent magnet, a pair of bifurcated pole pieces for said magnet, each of said pole pieces comprising a fixed limb and an adjustable limb, an armature clamped between said fixed limbs, an energizing coil pncircling said armature, a circuit changing device operated by said armature, an armature biasing device including a spring member attached to said armature and in alinement therewith, adjustable means for supportin the free end of said spring memher, a pointer carried by said adjustable a scale registering with said pointer in its movement.

In witness whereof, I hereunto subscribe my name this 6th day of December, A. D.

DANIEL D. MILLER. 

